I just thought I'd share my success of the day.
I used this program http://tftpd32.jounin.net/
taking the DHCP setup from this guide http://hugi.to/blog/archive/2006/12/...ll-via-windows
and made a folder on my windows computer, putting in the files mentioned in the "PXELinux configuration" section of the guide written by Eric Hameleers:
usb-and-pxe-installers/README_PXE.TXT (available in most of the slackware mirrors)
I had a bit of hassle trying to get the "pxelinux.0" file without access to a linux computer but I got it from here in the end
(it's in the "core" folder of that zip archive)
Hope this is of some use to someone, it took me a little while to find out a good way of installing Slackware using PXE without any access to an existing Linux computer. Enjoy!